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81.
Chouvarda I Maglaveras N Boufidou A Mohlas S Louridas G 《Medical & biological engineering & computing》2003,41(6):609-617
Non-stationary analysis of electrocardiograms (ECGs) using Wigner-Ville distribution is presented. Analysis was performed
on subjects with acute myocardial infarction who had undergone thrombolysis, in Holter recordings of lead V1. The distinction
between successfully and non-successfully thrombolysed patients was evaluated, based on time-frequency features of the Wigner-Ville
transformed ECGs at the sixth hour after lysis. Characteristic parameters were extracted from time-frequency areas, and linear
discriminant analysis was performed on these parameters, leading to a prediction index to distinguish the two classes. Thirteen
features were found statistically significant by t-test and were used for the classification with linear modelling. Out of
these features, four corresponded to frequencies lower than 25 Hz and higher than 50 Hz for, roughly, the QRS complex, five
features corresponded to all the frequency bands of, roughly, the ST area, and the last four features corresponded to the
T-wave. The feature-vector used in linear modelling was iteratively generated, and the iterative prediction found all 18 features
significant. The iterative method resulted in better classification than that of the standard statistical procedure (3.8%
error against 18.1% with the classic method). The evolution of the prediction index with time for the first 12 h was different
for the successfully and non-successfully thrombolysed groups. Specifically, in the successful thrombolysis group, oscillations
and variation with time were more obvious, indicating a possible difference in the dynamics of the cardiac system. 相似文献
82.
Müller T Ball T Kristeva-Feige R Mergner T Timmer J 《Medical & biological engineering & computing》2000,38(1):62-67
The aim is to describe a general approach to determining important electrode positions when measured electro-encephalogram
signals are used for classification. The approach is exemplified in the frame of the brain-computer interface, which crucially
depends on the classification of different brain states. To classify two brain states, e.g. planning of movement of right
and left index fingers, three different approaches are compared: classification using a physiologically motivated set of four
electrodes, a set determined by principal component analysis and electrodes determined by spatial pattern analysis. Spatial
pattern analysis enhances the classification rate significantly from 61.3±1.8% (with four electrodes) to 71.8±1.4%, whereas
the classification rate using principal component analysis is significantly lower (65.2±1.4%). Most of the 61 electrodes used
have no influence on the classification rate, so that, in future experiments, the setup can be simplified drastically to six
to eight electrodes without loss of information. 相似文献
83.
Mittal N Zhou Y Ung S Linares C Molloi S Kassab GS 《Annals of biomedical engineering》2005,33(8):1015-1026
A rigorous analysis of blood flow must be based on the branching pattern and vascular geometry of the full vascular circuit
of interest. It is experimentally difficult to reconstruct the entire vascular circuit of any organ because of the enormity
of the vessels. The objective of the present study was to develop a novel method for the reconstruction of the full coronary
vascular tree from partial measurements. Our method includes the use of data on those parts of the tree that are measured
to extrapolate the data on those parts that are missing. Specifically, a two-step approach was employed in the reconstruction
of the entire coronary arterial tree down to the capillary level. Vessels > 40 μm were reconstructed from cast data while
vessels < 40 μm were reconstructed from histological data. The cast data were reconstructed one-bifurcation at a time while
histological data were reconstructed one-sub-tree at a time by “cutting” and “pasting” of data from measured to missing vessels.
The reconstruction algorithm yielded a full arterial tree down to the first capillary bifurcation with 1.9, 2.04 and 1.15
million vessel segments for the right coronary artery (RCA), left anterior descending (LAD) and left circumflex (LCx) trees,
respectively. The node-to-node connectivity along with the diameter and length of every vessel segment was determined. Once
the full tree was reconstructed, we automated the assignment of order numbers, according to the diameter-defined Strahler
system, to every vessel segment in the tree. Consequently, the diameters, lengths, number of vessels, segments-per-element
ratio, connectivity and longitudinal matrices were determined for every order number. The present model establishes a morphological
foundation for future analysis of blood flow in the coronary circulation. 相似文献
84.
Gaëlle Dzangué-Tchoupou Kuberaka Mariampillai Loïs Bolko Damien Amelin Wladimir Mauhin Aurélien Corneau Catherine Blanc Yves Allenbach Olivier Benveniste 《Autoimmunity reviews》2019,18(4):325-333
Background
Myositis is a heterogeneous group of muscular auto-immune diseases with clinical and pathological criteria that allow the classification of patients into different sub-groups. Inclusion body myositis is the most frequent myositis above fifty years of age. Diagnosing inclusion body myositis requires expertise and is challenging. Little is known concerning the pathogenic mechanisms of this disease in which conventional suppressive-immune therapies are inefficacious.Objectives
Our aim was to deepen our understanding of the immune mechanisms involved in inclusion body myositis and identify specific biomarkers.Methods
Using a panel of thirty-six markers and mass cytometry, we performed deep immune profiling of peripheral blood cells from inclusion body myositis patients and healthy donors, divided into two cohorts: test and validation cohorts. Potential biomarkers were compared to myositis controls (anti-Jo1-, anti-3-hydroxyl-3-methylglutaryl CoA reductase-, and anti-signal recognition particle-positive patients).Results
Unsupervised analyses revealed substantial changes only within CD8+ cells. We observed an increase in the frequency of CD8+ cells that expressed high levels of T-bet, and containing mainly both effector and terminally differentiated memory cells. The senescent marker CD57 was overexpressed in CD8+T-bet+ cells of inclusion body myositis patients. As expected, senescent CD8+T-bet+ CD57+ cells of both patients and healthy donors were CD28nullCD27nullCD127null. Surprisingly, non-senescent CD8+T-bet+ CD57- cells in inclusion body myositis patients expressed lower levels of CD28, CD27, and CD127, and expressed higher levels of CD38 and HLA-DR compared to healthy donors. Using classification and regression trees alongside receiver operating characteristics curves, we identified and validated a frequency of CD8+T-bet+ cells >51.5% as a diagnostic biomarker specific to inclusion body myositis, compared to myositis control patients, with a sensitivity of 94.4%, a specificity of 88.5%, and an area under the curve of 0.97.Conclusion
Using a panel of thirty-six markers by mass cytometry, we identify an activated cell population (CD8+T-bet+ CD57- CD28lowCD27lowCD127low CD38+ HLA-DR+) which could play a role in the physiopathology of inclusion body myositis, and identify CD8+T-bet+ cells as a predominant biomarker of this disease. 相似文献85.
股骨上端形态曲线的测量、参数化与统计分析 总被引:1,自引:1,他引:1
通过对84根完好的中国人成人股骨标本进行正位和侧位两个方向的X线摄影,得到股骨正、侧两方位的X光片。对X光片上股骨上端髓腔内侧形态进行描绘,将描绘好的图像输入计算机,由计算机进行图像预处理后提取其曲线形态数据,并将形态数据参数化,从而得到可比较的、能准确表现股骨形态的量化数据,为股骨形态的分类分析和系列型人工髋关节的参数设计打下基础。 相似文献
86.
基于小波分解的多尺度医学图像融合技术 总被引:2,自引:1,他引:2
给出了一种基于小波分解的多尺度图像融合新方法。其基本思想是 ,先对源图像进行小波多尺度分解 ;其次 ,采用了基于区域特性量测选择的加权算子的融合规则进行小波系数融合 ;最后通过小波逆变换重构融合图像。实验结果表明 ,该融合方法十分有效 ,融合图像完好地显示了源图像各自的信息。 相似文献
87.
采用时域有限差分(FDTD)法结合遗传算法(GA)优化设计了适用于浅表生物组织高频测量的宽带同轴贴片探头,并用该探头测量了人体背部1~7GHz频带内的反射特性。优化设计出的圆形同轴贴片探头具有轴对称特点,辐射近场在生物组织中透人深、反射系数的频率响应特性好。所获得的人体背部反射特性的测量结果将为背部浅表组织电特性的重建提供有利的依据。 相似文献
88.
Vijay Gayam Venu M. Konala Srikanth Naramala Pavani Reddy Garlapati Mohamed A. Merghani Nirajan Regmi Mamtha Balla Sreedhar Adapa 《Journal of medical virology》2020,92(10):2181-2187
Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) is spreading at a rapid pace, and the World Health Organization declared it as pandemic on 11 March 2020. Mycoplasma pneumoniae is an "atypical" bacterial pathogen commonly known to cause respiratory illness in humans. The coinfection from SARS-CoV-2 and mycoplasma pneumonia is rarely reported in the literature to the best of our knowledge. We present a study in which 6 of 350 patients confirmed with COVID-19 were also diagnosed with M. pneumoniae infection. In this study, we described the clinical characteristics of patients with coinfection. Common symptoms at the onset of illness included fever (six [100%] patients); five (83.3%) patients had a cough, shortness of breath, and fatigue. The other symptoms were myalgia (66.6%), gastrointestinal symptoms (33.3%-50%), and altered mental status (16.7%). The laboratory parameters include lymphopenia, elevated erythrocyte sedimentation rate, C-reactive protein, lactate dehydrogenase, interleukin-6, serum ferritin, and D-dimer in all six (100%) patients. The chest X-ray at presentation showed bilateral infiltrates in all the patients (100%). We also described electrocardiogram findings, complications, and treatment during hospitalization in detail. One patient died during the hospital course. 相似文献
89.
Fine Mapping Functional Sites or Regions from Case-Control Data Using Haplotypes of Multiple Linked SNPs 总被引:1,自引:0,他引:1
Previously, we reported an algorithm for scanning a large number of tightly linked single nucleotide polymorphisms (SNPs) for LD mapping of functional sites or regions from a family‐based association design. In the present study, we extend our method to a case‐control design. We first use the expectation maximization (EM) algorithm to estimate haplotype frequencies of multiple linked SNPs, and follow this by constructing a contingency table statistic S for LD analysis, based on the estimated haplotype frequencies. An empirical p‐value is obtained based on the null distribution of the maximum of S (S *) from a large number (e.g., 1,000 or more) of randomized permutations. The proposed algorithm has been implemented in a computer program in which window searching for functional SNP sites can cover any number of loci without limitation, except that of computer storage. Unlike other programs for a case‐control design that always conduct tests at a fix window width, in our program after setting a maximum size of haplotype window width, for a given maximum window width all possible widths of haplotypes are utilized to find the maximum statistic S * for each locus under investigation. The sensitivity of the proposed algorithm has been examined with simulated and real genotyping datasets. Association analyses indicate that our program is powerful enough to detect most, if not all, functional SNPs simulated in the original model or identified in the original report. Moreover, the program is very flexible and can be used in either regional or genome‐wide scanning for association analysis with SNP markers. 相似文献
90.
Dr. Y. Fukuoka M. Noshiro H. Shindo H. Minamitani M. Ishikawa 《Medical & biological engineering & computing》1997,35(1):33-39
The nonlinearity included in the PCO
2 control system in humans is evaluated using the degree of nonlinearity based on a difference of residuals. An autoregressive
moving average (ARMA) model and neural networks (linear and nonlinear) are employed to model the system, and three types of
network (Jordan, Elman and fully interconnected) are compared. As the Jordan-type linear network cannot approximate respiratory
data accurately, the other two types and the ARMA model are used for the evaluation of the nonlinearity. The results of the
evaluation indicate that the linear assumption for the PCO
2 control system is invalid for three subjects out of seven. In particular, strong nonlinearity was observed for two subjects. 相似文献